Efforts in database design for observational scientific data concerned with path query specification and an access method design are discussed. The goal is to understand the issues related to scientific data and computations. The authors propose a representation of path queries and an access method, MoBiLe files, to capture space-time continuity. A survey on spatial indexing methods is given. The model of scientific data and computation is described. An example of scientific databases is given. Path queries are specified. The MoBiLe mapping functions and MoBiLe file design are described. The experiment used to verify the access methods and the data model are outlined. The experimental results and this observation and analysis are presented.